Icom Ic-h6 User manual

VHF

TRANSCEIVER

IC-H6

lcom

Inc.

TABLE

OF

CONTENTS

SECTION SPECIFICATIONS

........................................

. 1 - 1

SECTION 2

OPERATING

CONTROLS

..................................

. 2 - 1

"'

2

SECTION 3

CIRCUIT

DESCRIPTION

..................................

. 3 - 1

"'

4

3 - 1 RECEIVER

CIRCUITS

.................................

. 3 - 1

3-2

TRANSMITTER

CIRCUITS

.............................

.

3-2

3 - 3

PLL

CIRCUITS

.......................................

.

3-

2-

3

3 - 4

OTHER

CIRCUITRY

..................................

. 3 -

3-

4

SECTION 4

BLOCK

DIAGRAM

.......................................

. 4 - 1

SECTION 5 INSIDE VIEWS

..........................................

. 5 - 1

SECTION 6

MECHANICAL

PARTS

AND

DISASSEMBLY

.................

. 6 - 1

"'

5

6 - 1

DISASSEMBLY

OF

THE

CASES

.........................

. 6 - 1

6-2

DISASSEMBLY

OF

UNITS

.............................

.

6-

2-

3

6-3

PTT SPRING

ASSEMBLY

..............................

.

6-3

6

-4

TOP

PANEL

CONSTRUCTION

..........................

.

6-4

6 - 5

UNIT

BOTTOM

ASSEMBLY

............................

.

6-5

SECTION 7

MAINTENANCE

AND

ADJUSTMENT

.......................

. 7 - 1

"'

9

7 - 1

MEASURING

INSTRUMENTS

REQUIRED

FOR

ADJUSTMENT.

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 - 1

7 - 2

PRELIMINARY

CHECKS................................

7-

2

7 - 3

PREPARATION

AND

PROCEDURE BEFORE

SERVICING

........................................

. 7 -

2-

3

7-4

HOWTOCHECK

.....................................

. 7 -

3-

5

7 - 5 BASIC

ALIGNMENT

PROCEDURE

.......................

.

7-6"'

9

SECTION 8

BOARD

LAYOUT

........................................

. 8 - 1

"'

3

SECTION 9

VOLTAGE

CHARTS

......................................

. 9 - 1

"'

4

SECTION 10

TROUBLESHOOTING

....................................

. 10 -

1"'

4

SECTION

11

IC

SPECIFICATIONS

.....................................

.

11

- 1

"'

3

SECTION 12 PARTS

LIST

............................................

. 12 - 1

"'

4

SECTION 1 SPECIFICATIONS

GENERAL

Number

of

Semiconductors

Number

of

Channels

Channel Spacing

Frequency

Stability

Usable Temperature

Antenna Impedance

Power Supply Requirement

Current Drain at 8.4V

Dimensions

Weight

RECEIVER

Frequency

Range

Receiving System

Modulation Acceptance

Intermediate Frequency

Sensitivity

Squelch Sensitivity

Spurious

Response

Rejection Ratio

Selectivity

Intermodulation Rejection Ratio

Audio

Output

Power

Audio

Output

Impedance

TRANSMITTER

Frequency

Range

Output

Power

Emission Mode

Modulation System

Max. Frequency Deviation

Spurious Emission

Microphone

Transistors

FET

IC

43

3

5

Diodes 15 (not including diodes on the

matrix

board)

6 programmable channels (Transmit

and

Receive frequencies

are

pro-

grammable independently

for

each

channel)

Operation; Simplex, Semi-duplex

25KHz

(5KHz increments frequencies

are

programmable)

0.001 Percent

-20

Degrees

C

to

60

Degrees

C

(-4

Degrees

F

to

140

Degrees

F)

50 ohms unbalanced

DC

8.4

V;

with

attendant power pack IC-CM3,

DC

7

to

12V negative

ground

is

acceptable

Transmitting

At

2.5 watts

output

Approx.

700mA

Receiving

At

max audio

output

Approx.

130mA

Squelched Approx.

25mA

116.5mm(H) x 65mm(W) x 45mm (D)

without

power pack

Attendant

power pack, IC-CM3:

49mm(H)

x 65mm(W) x

35mm(D)

510g including power pack, IC-CM3,

and

flexible antenna

Specified 2MHz segment (5MHz

with

reduced specification)

within;

150.005 ~ 155.000MHz

155.005 ~ 160.000MHz

160.005

~

165.000MHz

165.000 ~ 170.000MHz

Double-conversion superheterodyne

16F3 ±7.5KHz (F3E 16KO)

1st: 16.9MHz

2nd:

455KHz

Less

than 0.5µV

for

20dB noise quieting

Less

than 0.4µV

for

12dB

SI

NAD

Less

than 0.4µV

More than 60dB

More than 65dB at adjacent channel

More than 60dB

More than 300mW at

10%

distortion

8 ohms

Specified 2MHz segment (5MHz

with

reduced specification)

2.5 Watts

(4

watts

with

10.BV battery pack IC-CM5)

16F3 (F3E 16KO)

Variable reactance frequency modulation

±5KHz

More than 60dB below carrier

Built-in electret condenser microphone

Optional speaker-microphone (IC-CM9)

can

be

used

1 - 1

SECTION 2 OPERATING CONTROLS

TOP

PANEL

@TRANSMIT/BATTERY

INDICATOR----~

...-----------·@CHANNEL

SELECT SWITCH

d)ANTENNA

CONNECTOR----

(j)

EXTERNAL

MIC

JACK-----'-

@EXTERNAL

SPEAKER

JACK

FRONT PANEL

@PUSH-TO-

TALK

(PTT)-----4

SWITCH

SPEAKER

MICROPHONE

2-1

~-----@SQUELCH

CONTROL

'--------@VOLUME

CONTROL

and

POWER SWITCH

REAR PANEL

l

:1.

@CHARGER

CONNECTOR

@BATTERY

CHARGE

INDICATOR

(])

ANTENNA CONNECTOR

Connect

the

supplied flexible antenna. An external antenna can be used, using a

BNC

connector.

®

TRANSMIT/BATTERY

INDICATOR

Illuminates

in

the transmit mode. Also indicates the battery condition; during transmission. The

voltage

of

Nickel-Cadmium batteries drops rapidly just before they are exhausted,

so

when this

indicator goes

out,

be sure

to

immediately stop using it, and charge the batteries again.

@ CHANNEL SELECT SWITCH

Selects one

of

the

programmed channels.

@)

SQUELCH CONTROL

Sets

the

squelch threshold level. To turn

OFF

the squelch function, rotate this control completely

counterclockwise. To set the threshold

level

higher, rotate

the

control clockwise.

@ VOLUME CONTROL

and

POWER

SWITCH

When the control

is

turned completely counterclockwise,

the

power

is

OFF.

By

turning

the

control

clockwise beyond

the

"click",

the

unit

is

turned

ON

and

the

audio

level

increases by further rotat-

ing

it clockwise.

@

EXTERNAL

SPEAKER JACK

When

an

external speaker (or

an

earphone)

is

used, connect it

to

this jack.

Use

a speaker with an

impedance of 8 ohms. When

the

external speaker

is

connected

the

built-in speaker does

not

function.

(J)

EXTERNAL

MIC JACK

When an external microphone

is

used, connect it

to

this jack. See

the

schematic for

the

proper

hookup. When the external microphone

is

connected the built-in microphone does

not

function.

The

IC-CM9

optional speaker-microphone can also be used.

Electret condenser microphone Dynamic microphone

Microphone

0

[_______..______!

~.

R

R=20-30K.11 PTT SWITCH

PTT SWITCH

@

PUSH

TO

TALK

(PTT) SWITCH

For transmission, press this switch and talk into

the

microphone with normal voice. The internal

microphone

is

of

the electret-condenser

type

and provides good pickup for

all

voice levels.

@ CHARGER CONNECTOR

Connects

to

the

output

plug

of

the

wall charger CM-25U/E

or

other

12V

DC

power source.

@ BATTERY CHARGE INDICATOR

Lights during battery charging.

2-2

SECTION

3 CIRCUIT DESCRIPTION

3 - 1 RECEIVER CIRCUITS

3 - 1 - 1 ANTENNA SWITCHING CIRCUIT

Signals from the antenna connector are fed

to

the antenna switching circuit through Chebyshev low-pass

filter consisting

of

L229, L230, C295, C297 and C298 in the PLL board.

The antenna switching circuit employs a quater wave switching circuit.

In

the

receive mode, switching diodes,

0216

and

0217

are turned OFF, and

they

make isolation against

the transmitter circuit and matching circuit, and the incoming signals are fed

to

the

RF

amplifier.

3 - 1 • 2

RF

AMPLIFIER

AND

FIRST MIXER

The signals from the switching circuit are fed

to

the

cascode amplifier

0101

and

0102.

The amplified signals are fed

to

the gate of the first mixer

0103

through the band-pass filter L102 -

L104, which reduces interference and intermodulation from

out

of the band signals.

To the source of

0103,

a 140MHz signal*

is

supplied from the PLL circuit

to

convert the RF signals into

16.9MHz first

IF

signals. (*This frequency differs depending on the version, and it can

be

calculated by

formula; "Receive frequency" -16.9MHz.)

The first

IF

signals are taken from the drain

of

0103

and fed

to

the

IF

circuit.

3 -

1·3

IF

CIRCUIT

The first

IF

signals from

0103

are fed

to

the

matched pair crystal filter F1101, then

IF

amplifiers

0104

and

0105.

The amplified signals are fed

to

IC101. IC101

is

composed

of

the second localoscillator, second mixer,

limiter amplifier, quadrature detector and active filter circuits.

The second local oscillator oscillates 16.445MHz with X101, and

is

fed

to

the second mixer with thefirst

IF

signals

to

convert into 455KHz second

IF

signals. The second

IF

signals are put

out

from

3, and

fed

to

external ceramic filter F1102 which has excellent selectivity, then fed

to

IC101

(Pin

5) again

to

amplify and detect.

The detected AF signals are put

out

from

9.

3 - 1 - 4

AF

AND

SQUELCH CIRCUITS

The detected AF signals are

put

6dB/Octave de-emphasis by integral circuit consisting of R117 and Cl26,

and fed

to

AF power amplifier IC102 through

the

VOLUME control R1,

to

obtain enough power

to

drive

the

speaker.

Noise components put

out

from

9 of

IC101

are fed

to

IC101

(Pin

10) again through the SQUELCH

control R2, which controls the squelch threshold level, filtered about 20KHz signal {noise) and

put

out

from Pin 11.

This signal (noise)

is

rectified by

0113,

integrated by R135, R136 and C136, and turns

0114

ON

and

turns OFF

the

regulator for AF power amplifier consisting of

0103,

0115

and

0116.

This reduces the current drain of the set,

in

the standby condition.

When

a signal

is

received, noise

is

suppressed by

the

signal and turns

0114

OFF and

the

regulator

is

turned

ON

and supplies regulated

voltage

to

the AF power amplifier, and incoming signal can be heard from

the

speaker.

In

the transmit mode, a voltage

is

applied

to

0114

and turns it ON, and turns the regulator OFF

the

same

as

in

the standby condition.

3-1

3 - 2 TRANSMITTER CIRCUITS

3-

2 - 1 MIC AMPLIFIER CIRCUIT

Audio signals from

the

microphone are fed

to

the

limiter amplifier, consisting

of

0125-

0128,

which

has 6dB/Octave response between 300Hz and 3KHz.

The

output

of

the

limiter amplifier

is

similar

to

rectangular waves and includes harmonics.

These harmonics are eliminated by

the

low-pass filter

0129,

which cuts 3KHz

or

higher.

Filtered signals are fed

to

the

VCO

in

the

PLL board

to

make modulation.

3-

2 · 2 MULTIPLIER AND DRIVER CIRCUITS

The

VCO

oscillates a half

of

a transmitting frequency,

thus

the

multiplier

0208

and

0209,

multiplies it

two

times

to

obtain 156MHz* transmitting frequency.

This 156MHz* signal

is

fed

to

amplifiers

0211and0212

through band-pass filter L219, L220 and L221,

L222

to

obtain 200 milliwatts pure 156MHz* signal. While switching from receive

to

transmit,

0210

is

turned

ON

by the charged voltage of C269, until the charged voltage has been discharged, and this

function cuts the bias voltage

of

0211,...,

0213.

This prevents transmission

of

unwanted signals.

(*This frequency differs depending

on

the

version.)

3 · 2 · 3

POWER

AMPLIFIER CIRCUIT

The

output

signals from

0212

is

fed

to

the

power amplifier

0213,

and amplified

to

2.5 watts.

In

the transmit mode,

0216

and

0217

are turned ON, and

0217

makes L228 have high-impedance and

0216

feeds

the

signals

to

the antenna through the low-pass filter.

3 · 3 PLL CIRCUITS

3 · 3 - 1 LOCAL OSCILLATOR CIRCUIT

The crystal oscillator

0206

oscillates 35.77625MHz* with X202 for receive, 40.00125MHz* with X203

for transmit, and

the

signal

at

two

times this frequency

is

taken from

the

collector

of

0207,

and fed

to

the

mixer of the PLL circuit.

(*These frequencies differ depending on the version.)

In

the

receive mode, R+6V

is

applied

to

0210

through R223, L211 and R227, and

0210

is

turned

ON

and selects X202.

In

the

transmit mode, T+6V

is

applied

to

0211

through R224, L212 and R228, and 0211

is

turned

ON

and selects X203.

3 - 3 · 2 MIXER,

LOW-PASS

FILTER AND AMPLIFIER CIRCUITS

The

output

signals from

the

local oscillator circuit and the VCO signals fed through buffer amplifiers

0202

and

0203

are mixed by

the

mixer

0204.

The

output

signals are fed

to

the low-pass filter

to

filter

out

only the signals below 7MHz, then fed

to

0205

to

be

amplified

to

proper drive

level

(more than

3Vp-p)

of

the

programmable divider IC201.

3 · 3 · 3 PROGRAMMABLE DIVIDER CIRCUIT

The input signals

at

Pin 2

of

IC201 are divided by

the

BCD

input signals from the matrix board

at

3-14.

The programmable divider

is

also called the 1/N counter and the

BCD

value

is

N.

The relationship between the operating frequency and

the

divide number N

is:

N (divide number

of

programmable divider) =

Receive (or Transmit) Frequency

(MHz)

-Local Osc Frequency

(MHz)

_

1000

0.005

3-2

3-

3 - 4 REFERENCE FREQUENCY GENERATOR CIRCUIT

Reference frequency generator IC203 consists of a crystal oscillator and a highspeed divider. X201 oscil-

lates

at

5.12MHz, which

is

divided by 2048. The 2.5KHz reference frequency

is

fed

to

phase

detector

IC202. This 2.5KHz reference frequency decides

the

variation step of the PLL

output

frequency.

3 - 3 - 5 PHASE DETECTOR

AND

LOOP

FILTER

CIRCUITS

Digital phase detector, IC202, detects

the

phase difference of

the

pulse signals

of

the

2.5KHz reference

frequency and

the

output

signal

of

the

programmable divider, and proportionately puts

out

pulse signals

at

3,

which becomes high impedance when

the

PLL

is

locked.

Pin 4

is

for detecting

the

lock failures and changes

to

ground level according

to

the

phase difference of

the

two

pulse signals. When

the

lock fails,

the

pulse signal from Pin 4

is

integrated by R202 and C215.

When

the

integrated voltage exceeds

the

junction voltage

of

0214's

base,

0214

is

turned

ON

and

then

0107

in

the

MAIN

boards

is

turned

ON.

The collector

of

0107

is

connected

to

the

base of

0108,

so

the

base voltage

of

0108

becomes ground

level, and

0108

and

0106

are

shut

off

to

prevent transmitting unwanted signals.

The

loop filter, consisting

of

R204, R205, R206, C213 and C214, converts

the

pulse signal from Pin 3

into a

DC

voltage and decides

the

response time

of

the

whole loop.

The

output

signals are fed

to

tuning diode D203

of

the

VCO circuit

as

the control voltage for

the

VCO

frequency set.

3-

3 - 6 VCO CIRCUIT

The VCO (Voltage-Controlled Oscilator)

is

a Colpitts circuit using

0201,

and oscillates

in

70 -80MHz

range.

The oscillator frequency

is

controlled by a

DC

voltage which

is

supplied from

the

loop filter

to

varactor

diode D203.

In

the

receive mode, R+6V

is

applied

to

D204's anode through L201, and D204

is

turned

ON

and shunts

C220. Thus

the

free-run frequency

of

the

VCO

is

lowered.

In

the

transmit mode, T+6V

is

applied

to

D204's

cathode

through D205 and L202, D204

is

turned

OFF,

and C220

is

inserted

in

the

oscillator circuit in series. Thus

the

free-run frequency of

the

VCO

is

increased.

In

the

same time,

the

VCO signal

is

frequency modulated by

the

audio signals from

the

microphone which are applied

to

the

gate

of

0201

and varies

0201

's mutual conductance.

3 -4 OTHER CIRCUITRY

3 - 4 - 1

POWER

SUPPLY CIRCUIT

The

regulated 6V

is

supplied

to

the

main circuits, so

that

the

set operates under a stable condition with

as low power voltage

as

possible.

The power supply voltage

is

fed

to

the

AF power amplifier through

the

squelch switching circuit and

to

the

6V regulator consisting

of

0117

-

0120

and zener diode D104. This regulated 6V

is

supplied

to

the

PLL circuit.

In

the

transmit mode,

the

base of

0123

is

grounded through R155,

the

microphone and

the

PTT switch,

and

0123

is

turned

ON. Thus

0106

and

0108

are

turned

ON

and T+6V

is

actuated, and supplied

to

the

transmitter circuit.

At

the

same time, T+6V turns

0112

ON, and

the

power supply voltage

is

applied

to

the

MIC

amplifier circuit through

0112.

In

the

receive mode,

0123

is

turned

OFF

and

the

bias voltage

of

0109

ON. Thus

the

R+6V

is

actuated

and supplied

to

the

PLL board

to

switch

the

local oscillator crystal and

the

driver transistors

of

the

transmitter

circuit.

At

the

same time, R+6V turns

ON

the

voltage boost circuit consisting

of

0110

and

0111,

and +6V

is

supplied

to

the

receiver circuit.

3-3

3-

4-

2 LED

INDICATOR

CIRCUIT

This LED

is

lit

in the transmit mode,

but

when the power supply voltage becomes

less

than 7V,

it

will

not

be

lit.

The power supply voltage

is

divided

by

R148 and R149, and applied

to

the

base

of

0121.

The emitter

of

0121

is

connected

to

the regulated

6V

source.

When

the power supply voltage

is

more than 7V,

0121

is

turned OFF,

0122

is

turned ON and

T+6V

is

applied

to

the LED through

0122

and R150, and

the LED

is

lit.

3-

4-

3 DIODE

MATRIX

BOARD

The

set

incorporates a diode

matrix

board

to

determine its operation frequencies, and six channels

each

can

be

programmed

into

the board

for

transmit and receive.

+6V

is

applied

to

each

channel line, one

of

receive channels 1 - 6 and transmit channel 1 - 6, through

the channel select switch, and

it

is

converted

to

BCD

codes

by diodes programmed

into

the board, then

fed

to

IC201

to

determine

an

operation frequency.

When duplex transmit

function

is

required, calculate

each

N value

for

transmit frequency and receive

frequency and program diodes

into

the board independently.

The receive

only

function

is

provided

for

channel 2 - Channel 6 by inserting a diode

into

the receive

only

line.

At

this time, a voltage

is

applied

to

the

base

of

0107

on the

MAIN

board through R404, and

it

turns

0107

ON and

0106

OFF. Thus, the

set

does

not

turn

to

the transmit mode,

even

if

the PTT

switch

is

depressed.

Crystal Frequency Chart

Operating Frequency

Range

Crystal Frequency (MHz) Local Oscillator

X202

(Receive)

X203

(Transmit) Frequency (MHz)

150.005 -155.000MHz 32.02625 36.25125 145.005

155.005 -160.000MHz 33.27625 37.50125 150.005

160.005-

165.000MHz 34.52625 38.75125 155.005

165.005 -170.000M

Hz

35.77625 40.00125 160.005

NOTE: The local oscillator frequency

for

calculation N value

is

the

four

times

of

the crystal frequency.

3-4

""'

I

16.9MHz

455KHz

RF

Amp

' Ceramic Noise Squelch

1st Mixer Crystal 1st

IF

Amp

,.

0101

r-+

,.

Filter

~

Filter

Detector

~

Control

2SC2026

0103

F1101

0104,

0105

--

0113

r

,___

F1102

0114,

0115

0102

2SK192 16M15B2 2SC2668 x 2

2SC2668

CFU455E2

2SA1048 2SC2458 x 2

f

~VCC

~

I v I Squelch [

Indicator

Regulator

T/R

Switch

~

-.j

2nd

Mixer

2nd

~

Noise

Amp~

Control

0117

2SK192

0106,

109,

111

~R6V

IF

Amp

re--

0118

2SB562 rl>

116,112

t

AF

Powoc

-.aj

0121,

0122

0119,

0120

2SA1048 x 2 2SC2458 x 2

4J

r<rcJ

~

6V

LED

Power

Switch

x2

Multiplier

I

0209

2SC2668

Battery Cl.

Pack

X2

Microphone

D-

Multiplier

-

0207

2SC2668

Mic

Amp

0125·

126

Limiter

2SC2458 x 2

~

0128

0127

2SA1048 2SC2458

......

v

in

Transmit mode

----~~

..

in Receive mode

-----1[>

in Common mode

~

...

~

2SA1048 x 5

0107,108,110

2SC2458 x 3

..L

t

~

T

T6V

R6V X101

16.445MHz

Buffer

Amp

Driver

0211

~

0212

-£;'.>

2SC383 2SC2053

"'7

Crystal

X202(R}*

l Switch

H>

X203(T)*

9-i)

D210-D212

1SS53 x 3

(*Refer

to

page

3 - 4)

I

Buffer

Amp

Buffer

Amp

0208

0202,

0203

2SC2026 2SC2668 x 2

Lf

1'

T

Low-pass vco

Filter

FM Modulator

0129

~

0201

2SK192

(}-

2SC2458 D203 1SV50

.,.

~FM

Detect

A,;>.

Amp

~

2nd

LO

...--/'¢.f""

IC102

BA526

....

IF

IC

Volume

Speaker

IC101 MC3357

Antenna

Power

Amp

RF T

T/R

Switch Low-Pass

0213

f-l;i D216, D217

llf-(;1I

2SC1947

Filter

1SS53 x 2

Mute

Switch

X2

0210

Crystal

OSC

2SC2458

~

PLL

Mixer

Multiplier

-{>

-j)

Low-pass

0214

0206

0204

2SA1048

2SC2668

Filter

2SC2026

~

'i7

Oscillator Level Channel

Switch

l Divider Converter 0

0-{)

(1/2048)

T

IC203

0205

0

X201 TC5082 2SC945

5.12MHz

2.5KHz

'i7

Phase

Programmable

Matrix

Board

Detector Divider

0401

Loop

Filter

kl- IC202

<I-

IC201

Fl-

2SA1048 <I-

0402

TC5081 TC9122 2SC2458

l

en

m

(')

::!

0

:z

.i::o

al

r-

0

(')

;;i:::

0

)>

G')

J:l

)>

s::

SECTION 5 INSIDE VIEWS

MAIN

UNIT

Pll

UNIT

X202

(PLL

RX

LO

Crystal)------==

L215

•

L216

(PLL

LO

Output

Filter!----"~

J201 •J202

(Matrix

Board

Connectors)---=-"~--4

lC201

{TC9122

Programmable

Divider)---='-

IC202

(TC5081

Phase

Detector)----=-

IC203 (TC5082

Oscillator/Divider)---=-

X201 (5.12MHz Reference

Frequencv--~

Crystal)

L217·

L218

(RX

LO Band·Pass

Filter}---:

-

::--=:;----1c101

(MC3357

IF

Circuit

IC)

-:=-----L107

(Quadrature Coil)

::::::,,..-::::---Fl102

l455KHz

Ceramic FHterl

X101 (16.445MHz 2nd

LO

Crystal)

.:.=:-----C291

{PA

Output

Trimmer)

r:-----C290

(PA

Output

Trimmer)

=:::=:;,=.,.:=-----

L212

(X203

Frequency Adjust)

-~---------0213

{PA 2SC1947l

-=----

L211

(X202

Frequency

Adjust)

~----C286

(Driver

Output

Trimmer)

.;;.o:;::-----C285

(Driver

Output

Trimmer!

i..,,..;::::::;;::;;:;.::;.-L203 (VCO Free-Run Frequency Adjust)

iiiiiirir----------VCO

Circuit

5-1

SECTION 6 MECHANICAL

PARTS

AND DISASSEMBLY

6 - 1 DISASSEMBLY OF THE

CASES

1.

Turn the power switch off and remove the power pack.

2. Remove two screws

(('.)

on

the

rear panel and four screws on the bottom

as

shown

in

the figure.

®

3. Remove the front panel

as

shown

in

the

figure. At this time, be

sure not

to

damage the engaged parts at

the

top

(circled with

dotted lines).

open the bottom slightly and slide the front panel down-

wards.

4. Slide

the

PTT Button upward, and then remove the rear panel.

J

6-1

6 - 2 DISASSEMBLY

OF

UNITS

REAR

PANEL

30283

M2

x 12

ifJRound head

Screw x 2

~__.,..,:;==;::>,

PTT BUTTON

42289

FRONT

PANEL

30222

1. When you wish

to

program some operation frequencies (channels), remove

the

rear panel,

then

unplug

the

connectors between

the

matrix board and PLL board, and tilt

the

matrix board

as

shown

in

the

figure.

When you wish

to

remove

the

matrix board from

the

set, unplug

the

two connectors located on

the

front

side end

of

the

board.

When you wish

to

remove

the

matrix board, unplug these connectors.

6-2

To see

the

printed sides of the

PC

boards, open

the

chassis by removing two screws

©located

above

and below·the

PTT

spring.

©

Dmn----

M2x4l'B

Flat

head

screw

PTT SPRING

©

l)mi----111

M2x4C-f!

Flat head screw

0

MAIN

UNIT

(PARTS SIDE)

PLL

UNIT

(PRINTED SIDE)

~-,...-.....,.,,..~

CONTACT

HOLDER~.....,.__,-~

CONTACT

SPRING 41737

41750

6 - 3 PTT SPRING ASSEMBLY

(HOW TO REPLACE PTT SPRING)

1. The

PTf

spring

is

soldered at its

top

as

shown

in

the figure.

2. Remove the old spring by heating the soldered point.

3. Solder

the

hole at

the

top

of

the new spring.

4.

Make

sure

that

the

new spring

is

soldered on parallel

to

the

chassis.

Soldered

point

,

,,

, '

/ '

PTT

Spring

41746

6-3

CHASSIS

A,

B

30284

0

MAIN

UNIT

(PRINTED

SIDE)

6-4

TOP

PANEL CONSTRUCTION

BNC-RM--....i

©

+--TOP

PANEL

WASHER lr.:1

=.==1==~===

+--CHASSIS

BNC

NUT~

~

_l/

TOP

PLATE

LED 42062

SLC-26UR (C-00964)

.--~~-.---~-KNOB

N-56

42037

i i

~

VR

NUT(A)

I T 42061

[ I

b-TOP

PANEL

-30282

======:::i.--CHASSIS

A, B

~

30284

-WASHER

~-+------

R2

(SOL)

K12141014-5N1212

-10KB

~KNOB

~

N-55

i 42036

2.5ql

NUT]

13.5ql

NUT

j

b-TOP

PANEL

~VRNUT(B)

I 42061

~f~~T_o_P_P_A_N_E_L~_30_2_s_2~~-i--

======-t--CHASSIS

A, B

.,.-..l

__

WASHER

J2 (EXT

SP)

HSJ0296-01-150

~J3(MIC)

HSJ0289-01-050

6-4

II

CHASSIS A, B l

30284

1r

6 - 5

UNIT

BOTTOM ASSEMBLY

(BOTTOM VIEW)

1.

2.

t;:::.========:=:=:=:=::::;:!\4---FRONT

PANEL

.....---.----SLIDING

GUIDE (A)

@

~~~~~-'--+--1----CONT

ACT

HOLDER

©t>

@

~~~g)J

1--------2====nr=r--i----CONT

ACT

SPRING

~==================;r---

REAR PANEL

(HOW TO REPLACE CONTACT SPRING)

Remove

the

sliding guide by removing the four screws

as

shown.

Remove

the

contact

spring

by

removing

the

two screws

as

shown.

3. Set

the

new

contact

spring so

that

the

split

of

the

spring

is

on

the

positive side and

the

other

end on

the

negative side.

4. Tighten

the

two

screws.

~--

-

--

- - - - - u - - - - -

--

~

i

~

SLIDING

GUIDE

(A)

41751

M2.6

x 6

f,

Flat

head

Screw x 4

I

~~

!•I~

~

M2.6

NUT

x 2

1~-.I

-----

~'

t+-----;t~I

CONTA;;-73~0LDER

~

6-5

' I

CONTACT

SPRING

M2.6x

6 f

"'·Truss head

screw

41750

SPRING WASHER

I

M2.6

x 6

~I

'r

Round

head

screw

SECTION 7 MAINTENANCE AND ADJUSTMENT

7

-1

MEASURING INSTRUMENTS REQUIRED

FOR

ADJUSTMENT

(1) FREQUENCY COUNTER

(2)

SIGNAL GENERATOR

(3) MULTIMETER

(4) AC MILLIVOLTMETER

(5)

RF

VOLTMETER

(6)

RF

WATTMETER (Terminated Type)

(7)

AF OSCILLATOR

(8)

OSCILLOSCOPE

(9)

FM DEVIATION METER

(10) DIRECTIONAL COUPLER

(11) AMPERMETER

(12) DUMMY LOAD

OR

EXTERNAL

SPEAKER

(13) VOLTAGE REGULATED

POWER

SUPPLY

FREQUENCY RANGE

ACCURACY

SENSITIVITY

FREQUENCY RANGE

OUTPUT VOLTAGE

50Krl/Volt

or

better

MEASURING RANGE

FREQUENCY RANGE

MEASURING RANGE

FREQUENCY RANGE

IMPEDANCE

SWR

OUTPUT FREQUENCY

OUTPUT VOLTAGE

DISTORTION

FREQUENCY RANGE

MEASURING RANGE

FREQUENCY RANGE

MEASURING RANGE

FREQUENCY RANGE

MEASURING RANGE

IMPEDANCE

OUTPUT VOLTAGE

CAPACITY

7-1

0.1·180MHz

BETTER THAN ±1

ppm

100mV or BETTER

0.1MHz · 180MHz

-20

· 90dB

(OdB

= 1µV)

10mV · 2V

0.1·180MHz

0.01·10V

5 -

10

Watts

140 -180MHz

50

OHMS

LESS

THAN

1.1

200-

3000Hz

0-

200mV

LESS

THAN

0.1

%

DC

-15MHz

0.01 -10V

140-

180MHz

0-

±10KHz

140-

180MHz

0-1.5A

DC

8 OHMS

5"'

11

V

DC

(adjustable)

1.5A

OR

MORE

7 - 2 PRELIMINARY

CHECKS

7 -2• 1 TRANSMITTER OUTPUT CHECKS

Power

Supply

8.4Vor

Battery (IC-CM3)

1. Connect a 50 ohms RF

wattmeter

to

the ANT connector.

50.Q

Power

M.

2. Setting

the

Set

to

any programmed channel and key

the

transmitter. Observe

the

RF power OUT-

PUT.

3.

Power

output

should be 2.5 -

3.0

watts

at

rated input (power supply) voltage.

7 · 2 · 2 RECEIVER

CHECKS

Make

all

checks

at

8.4V DC

1. Settings

of

controls and switches

Power switch

ON

Squelch Control Fully counterclockwise

Frequency Any programmed channel

Oscillo-

scope

EXT.

SP.

Audio

V.M.

Power

Supply

S.G.

EXT

SP

o

JACK

,.,..._.i......w......,,,.,....

0

8.4V

2. Connect an AF voltmeter

to

the

EXT

SP

jack and set

the

SOL control fully counterclockwise.

3. Connect

the

RF

output

of

a VHF signal generator

to

the

ANT connector.

4. Adjust the VOL control and the AF voltmeter range.

Adjust

the

VOL control for a full scale reading

on

the

AF voltmeter. Don't change

the

VOL control

setting after this adjustment.

5. Set the signal generator

to

the

receiving frequency and adjust the

output

level

of

the

signal generator

until

the

AF voltmeter shows a 20dB decrease

in

reading.

6. The signal generator

output

voltage

at

this point

is

the

20dB quieting sensitivity.

7 - 3 PREPARATION AND PROCEDURE BEFORE SERVICING

1.

Confirm defective operation and check

to

make sure setup or external sources are not

the

cause

of

the

problem.

2. Proper tools and measuring instruments are required for repair and adjustment.

Don't

try

to

repair

or modify

without

them.

7-2

3. Remove the transceiver case

as

shown on

Page

6 -

1.

Use

a screw driver

that

fits the screw.

4.

To open the hinge chassis remove

the

two screws

as

shown on

Page

6 - 2.

5. Attach an 8.0 ~ 11.0V

DC

external power source

to

the battery clip or screw.

Be

sure

to

check

the

polarity.

6.

In

the

case of a transmission problem, a dummy load should be connected

to

the

antenna connector.

In

the case

of

a receiving problem, an antenna or signal generator

is

connected

to

the

antenna

connector.

Be

careful not

to

transmit into the signal generator.

7.

Recheck for

the

suspected malfunction with the power switch on.

8. Check

the

defective circuit and measure the

DC

voltages of the collector, base and emitter of each

transistor.

9.

When

checking a transmission problem, it

is

convenient

to

short circuit an accessory mic connector

plug and insert it, turning on the transmitter.

7 - 4 HOW TO CHECK

7-4-1

RECEIVE

1. Check

the

frequency of P.L.L. unit when you are unable

to

receive with a strong signal present and

noise present when turning up the AF volume.

2.

When

no noise

is

present

at

the speaker, check audio frequency amplifier or 6V regulator first.

3. Inject

RF

through a

O.OlµF

capacitor from an

FM

signal generator modulated with 1

KHz

audio

modulation (FM),

to

points

(A)

through

(D)

in

order, check for receiver output.

(A)

= Selected channel frequency

(B)

= Selected channel frequency

(C)

= 16.900MHz

(D)

= 16.900MHz

4. Check (E) and (F) with

an

oscilloscope, for demodulated

output

in

the

audio frequency range.

A B c D

(0)

7-3

E F G

,lv'\_,,,r:::-:i

~)mm

illl.1

t

1:tt-31H

7 - 4 -2 TRANSMITTER

1. Check (A)"through (G) in

order

with RF

voltmeter.

2. When

the

transmitter

output

is

low, check regulated

power

supply voltage first,

do

not

turn

coil

trimmers.

3.

When transmission

is

normal, RF

is

present

and

it

is

not

possible

to

measure

the

DC voltage

accurately

with

a

voltmeter.

(E) (F) (G)

..

7-

4-

3 MODULATION

,17\~·-·9

~

Z09lD1

\i£iJ

E

210

·©""

\iii)

-~

""

\ill)

·©'::;@)

·©o~•M@)

'~""~

1.

Put

a signal

into

the

EXT

MIC

connector

(1KHz40mV)

with

an AF oscillator

or

an

external

mic.

2. Check

the

AF

voltages (A)

through

(E) in

order

with an oscilloscope.

(A)

(B) (C)

7-4

(E) (D)

,r.7\,.,,,,

~

~104-5

\ii..il

r

101-e112

1>•-s11t-20

.0.,~,,,~

~111113\.lrn

E

12•-31?7

·®

'"""

CiiiJ

·~

""

(ii§)

·©'~"·@)

Icom IC-H6 User manual

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